Intel(R) Xeon(R) CPU E5-2630 v4 @ 2.20GHz, 4 cores
OS type and version
Ubuntu Linux 20.04.4
Virtualmin version
7.0-4
Guys, I started having problems with emails on my server, I don’t remember making any changes. Everything was working until the 8th, now, I don’t receive any more e-mails, but I send them with ease. I accessed the mail log and discovered SEVERAL records like this (some data I will censor for privacy)
May 11 09:45:55 NAMEOFMYMACHINE postfix/smtpd[314319]: NOQUEUE: reject: RCPT from s4.fe.registro.br[200.160.2.29]: 451 4.3.5 <address@ofmydomain.com.br>: Recipient address rejected: Server configuration problem; from=<nicmailer@registro.br> to=<address@ofmydomain.com.br> proto=ESMTP helo=<s4.fe.registro.br>
May 11 09:45:55 NAMEOFMYMACHINE postfix/smtpd[314319]: disconnect from s4.fe.registro.br[200.160.2.29] ehlo=2 starttls=1 mail=1 rcpt=0/1 data=0/1 rset=1 quit=1 commands=6/8
May 11 09:45:56 NAMEOFMYMACHINE postfix/smtpd[312237]: disconnect from unknown[IP ADDRESS] ehlo=1 auth=0/1 rset=1 quit=1 commands=3/4
address@ofmydomain.com.br it’s just a censored email not to reveal the real content.
This has been happening with all my accounts (servers) hosted on my machine. I’m very layman, so if you have a solution, try to be as clear as I don’t have all the technical knowledge, but I’m trying to learn. Thank you very much.
Does Postfix accepts connections on port 25? Presumably it does, based on logs but anyway, what is the output of the following commad:
netstat -tnlp | grep 25
Does restarting Postfix service by running systemctl restart postfix fixes the problem? Also, what is the output of systemctl status postfix command ran right after restart?
It is hard to tell off-hand what is wrong exactly, without looking into master.cf and main.cf files.
Do you remember if you made any mail-related changes on Virtualmin side?
root@MYMACHINE:~# systemctl status postfix
● postfix.service - Postfix Mail Transport Agent
Loaded: loaded (/lib/systemd/system/postfix.service; enabled; vendor prese>
Active: active (exited) since Thu 2022-05-12 07:10:48 CDT; 1min 25s ago
Process: 100170 ExecStart=/bin/true (code=exited, status=0/SUCCESS)
Main PID: 100170 (code=exited, status=0/SUCCESS)
May 12 07:10:48 myaddress.contaboserver.net systemd[1]: Starting Postfix Mail T>
May 12 07:10:48 myaddress.contaboserver.net systemd[1]: Finished Postfix Mail T>
lines 1-8/8 (END)
I remember just do try greylisting and blacklisting some domains, but i already deleted that records. I know they may not even be related to the problem, but in the concern of reversing I already undid everything I had tried to do.
#
# Postfix master process configuration file. For details on the format
# of the file, see the master(5) manual page (command: "man 5 master" or
# on-line: http://www.postfix.org/master.5.html).
#
# Do not forget to execute "postfix reload" after editing this file.
#
# ==========================================================================
# service type private unpriv chroot wakeup maxproc command + args
# (yes) (yes) (no) (never) (100)
# ==========================================================================
smtp inet n - y - - smtpd -o smtpd_sasl_auth_enable=yes -o smtpd_tls_security_level=may
#smtp inet n - y - 1 postscreen
#smtpd pass - - y - - smtpd
#dnsblog unix - - y - 0 dnsblog
#tlsproxy unix - - y - 0 tlsproxy
#submission inet n - y - - smtpd
# -o syslog_name=postfix/submission
# -o smtpd_tls_security_level=encrypt
# -o smtpd_sasl_auth_enable=yes
# -o smtpd_tls_auth_only=yes
# -o smtpd_reject_unlisted_recipient=no
# -o smtpd_client_restrictions=$mua_client_restrictions
# -o smtpd_helo_restrictions=$mua_helo_restrictions
# -o smtpd_sender_restrictions=$mua_sender_restrictions
# -o smtpd_recipient_restrictions=
# -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
# -o milter_macro_daemon_name=ORIGINATING
#smtps inet n - y - - smtpd
# -o syslog_name=postfix/smtps
# -o smtpd_tls_wrappermode=yes
# -o smtpd_sasl_auth_enable=yes
# -o smtpd_reject_unlisted_recipient=no
# -o smtpd_client_restrictions=$mua_client_restrictions
# -o smtpd_helo_restrictions=$mua_helo_restrictions
# -o smtpd_sender_restrictions=$mua_sender_restrictions
# -o smtpd_recipient_restrictions=
# -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
# -o milter_macro_daemon_name=ORIGINATING
#628 inet n - y - - qmqpd
pickup unix n - y 60 1 pickup
cleanup unix n - y - 0 cleanup
qmgr unix n - n 300 1 qmgr
#qmgr unix n - n 300 1 oqmgr
tlsmgr unix - - y 1000? 1 tlsmgr
rewrite unix - - y - - trivial-rewrite
bounce unix - - y - 0 bounce
defer unix - - y - 0 bounce
trace unix - - y - 0 bounce
verify unix - - y - 1 verify
flush unix n - y 1000? 0 flush
proxymap unix - - n - - proxymap
proxywrite unix - - n - 1 proxymap
smtp unix - - y - - smtp
relay unix - - y - - smtp
-o syslog_name=postfix/$service_name
# -o smtp_helo_timeout=5 -o smtp_connect_timeout=5
showq unix n - y - - showq
error unix - - y - - error
retry unix - - y - - error
discard unix - - y - - discard
local unix - n n - - local
virtual unix - n n - - virtual
lmtp unix - - y - - lmtp
anvil unix - - y - 1 anvil
scache unix - - y - 1 scache
postlog unix-dgram n - n - 1 postlogd
#
# ====================================================================
# Interfaces to non-Postfix software. Be sure to examine the manual
# pages of the non-Postfix software to find out what options it wants.
#
# Many of the following services use the Postfix pipe(8) delivery
# agent. See the pipe(8) man page for information about ${recipient}
# and other message envelope options.
# ====================================================================
#
# maildrop. See the Postfix MAILDROP_README file for details.
# Also specify in main.cf: maildrop_destination_recipient_limit=1
#
maildrop unix - n n - - pipe
flags=DRhu user=vmail argv=/usr/bin/maildrop -d ${recipient}
#
# ====================================================================
#
# Recent Cyrus versions can use the existing "lmtp" master.cf entry.
#
# Specify in cyrus.conf:
# lmtp cmd="lmtpd -a" listen="localhost:lmtp" proto=tcp4
#
# Specify in main.cf one or more of the following:
# mailbox_transport = lmtp:inet:localhost
# virtual_transport = lmtp:inet:localhost
#
# ====================================================================
#
# Cyrus 2.1.5 (Amos Gouaux)
# Also specify in main.cf: cyrus_destination_recipient_limit=1
#
#cyrus unix - n n - - pipe
# user=cyrus argv=/cyrus/bin/deliver -e -r ${sender} -m ${extension} ${user}
#
# ====================================================================
# Old example of delivery via Cyrus.
#
#old-cyrus unix - n n - - pipe
# flags=R user=cyrus argv=/cyrus/bin/deliver -e -m ${extension} ${user}
#
# ====================================================================
#
# See the Postfix UUCP_README file for configuration details.
#
uucp unix - n n - - pipe
flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient)
#
# Other external delivery methods.
#
ifmail unix - n n - - pipe
flags=F user=ftn argv=/usr/lib/ifmail/ifmail -r $nexthop ($recipient)
bsmtp unix - n n - - pipe
flags=Fq. user=bsmtp argv=/usr/lib/bsmtp/bsmtp -t$nexthop -f$sender $recipient
scalemail-backend unix - n n - 2 pipe
flags=R user=scalemail argv=/usr/lib/scalemail/bin/scalemail-store ${nexthop} ${user} ${extension}
mailman unix - n n - - pipe
flags=FR user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py
${nexthop} ${user}
submission inet n - y - - smtpd -o smtpd_sasl_auth_enable=yes -o smtpd_tls_security_level=may
smtps inet n - y - - smtpd -o smtpd_sasl_auth_enable=yes -o smtpd_tls_security_level=may -o smtpd_tls_wrappermode=yes
Main.cf:
# See /usr/share/postfix/main.cf.dist for a commented, more complete version
# Debian specific: Specifying a file name will cause the first
# line of that file to be used as the name. The Debian default
# is /etc/mailname.
#myorigin = /etc/mailname
smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no
# appending .domain is the MUA's job.
append_dot_mydomain = no
# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h
readme_directory = no
# See http://www.postfix.org/COMPATIBILITY_README.html -- default to 2 on
# fresh installs.
compatibility_level = 2
# TLS parameters
smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
smtpd_tls_security_level = may
smtp_tls_CApath=/etc/ssl/certs
smtp_tls_security_level = may
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = MYADDRESS.contaboserver.net
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
mydestination = $myhostname, _HOSTNAME_, MYADDRESS.contaboserver.net, localhost.contaboserver.net, localhost
relayhost =
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
inet_protocols = all
virtual_alias_maps = hash:/etc/postfix/virtual
sender_bcc_maps = hash:/etc/postfix/bcc
sender_dependent_default_transport_maps = hash:/etc/postfix/dependent
mailbox_command = /usr/bin/procmail-wrapper -o -a $DOMAIN -d $LOGNAME
home_mailbox = Maildir/
smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
broken_sasl_auth_clients = yes
smtpd_recipient_restrictions = permit_mynetworks permit_sasl_authenticated reject_unauth_destination check_policy_service inet:127.0.0.1:10023
allow_percent_hack = no
tls_server_sni_maps = hash:/etc/postfix/sni_map
How did this happen? I really dont know. Im am a newbie user so i didnt even get closer of this codes, as you know early, i even found the main.cf without your guys help.
I was trying to block a domain from send us e-mail, so i start to look at SpamAssassin, i dont know if was ClamAV or something else that make sense to you. I remember that i tryed to enable On ClamAV Server at Spam and Virus Scanning section and i remember that the pages refreshes and the button stays the same thing, like it wasnt enable yet. So i just give up and i keep traveling around the panel for see solutions to block a domain to send for a specific user. Then i found greylisting and i was trying to block that domain. And that was it.